The present invention relates to a control method and a control unit therefor, and more particularly, it relates to a general operation control method in which a group of operating units performing a certain operation are managed to perform regular operation control following a prescribed rule, and to a control unit therefor.
Referring to drawings, a conventional general operation control method and a control unit therefor are now described with reference to a multi-optical axis photoelectric switch.
A multi-optical axis photoelectric switch has generally been employed as a safety for a press machine or as an intrusion warning unit in a dangerous zone. Such a multi-optical axis photoelectric switch is structured as follows: A projector having a plurality of projective elements and a photoreceiver having a plurality of photodetectors corresponding to the respective ones of the plurality of projective elements are arranged to oppose each other. Optical axes are formed between the respective ones of these plurality of projective elements and plurality of photodetectors, whereby a number of optical axes (optical paths) are formed between the projector and the photoreceiver. A detection area is set between the projector and the photoreceiver, the plurality of projective elements are successively rendered to emit light, and photoreceiving operations are performed by the photodetectors corresponding to the respective projective elements in a state synchronized with the projection timings. In the multi-optical axis photoelectric switch, photoreceiving signals by the photodetectors disappear when a light intercepting object is present in the detection area, and hence an object detection signal can be outputted by determining light intercepted states of the optical axes on the basis thereof. In a place where the multi-optical axis photoelectric switch is used, a press unit is stopped, or an intruder into a dangerous zone in a factory is detected and a warning is issued on the basis of such an object detection signal, for preventing an accident.
In such a multi-optical axis photoelectric switch, a synchronous signal transmitted from the projector to the photoreceiver is employed for synchronizing the timings of projecting operations and the timings of the photoreceiving operations. Such a synchronous signal may be transmitted from the photoreceiver to the projector. As transmission means for the synchronous signal, an electric one employing a wire, or an optical one employing light may be employed.
A specific example of the structure of the multi-optical axis photoelectric switch is now described. FIG. 20 is a block diagram showing the structure of a multi-optical axis photoelectric switch. Referring to FIG. 20, this multi-optical axis photoelectric switch is structured by a pair of projector 1 and photoreceiver 2. The projector 1 includes a sequential projection circuit 3, a timing circuit 4, and a plurality of projective elements 101 to 106. The photoreceiver 2 includes a photoreceiving selection circuit 6, a timing circuit 5, a plurality of photodetectors 201 to 206, an amplifier circuit 7, a microcomputer 8 and an output circuit 9.
The projective elements 101 to 106, each formed by a light emitting diode or a laser diode, successively perform projection one by one. The photodetectors 201 to 206 are arranged opposing to corresponding ones of the respective projective elements 101 to 106, and receive light projected from the corresponding projective elements. Each of the photodetectors 201 to 206, formed by a photodiode or a phototransistor, converts the received light to an electric signal and outputs the same. The projective elements 101 to 106 and the photodetectors 201 to 206 are provided in a one-to-one basis, and the corresponding projective elements and photodetectors are arranged opposed to each other at a prescribed distance in a detection area. Adjacent projective elements and the adjacent photodetectors are each arranged at prescribed intervals. A plurality of optical axes (optical paths) are formed by such a plurality of projective elements 101 to 106 and plurality of photodetectors 201 to 206.
The timing circuit 4 supplies a timing signal defining a projection timing to the sequential projection circuit 3, while supplying a synchronous signal for synchronizing a projecting operation and a photoreceiving operation to the timing circuit 5. The sequential projection circuit 3 is a circuit for successively driving the projective elements 101 to 106 one by one, and drives the projective elements 101 to 106 by successively feeding a driving current to the projective elements 101 to 106 in response to the timing signal received from the timing circuit 4.
The timing circuit 5 supplies a timing signal defining a photoreceiving timing to the photoreceiving selection circuit 6 in synchronization with the synchronous signal received from the timing circuit 4, while supplying a signal indicating the photoreceiving timing to the microcomputer 8. The photoreceiving selection circuit 6 is a circuit for performing selective control of photoreceiving by the photodetectors 201 to 206, and performs the following operation: The photoreceiving selection circuit 6 selects, in synchronization with a projective element performing a projecting operation, the corresponding photodetector on the basis of the timing signal supplied from the timing circuit 5, and operates the photodetector to a photodetectable state. Thus, the corresponding projective elements and photodetectors successively perform projection and photoreceiving pair by pair. Further, the photoreceiving selection circuit 6 receive a photoreceiving signal supplied in response to photoreception by the photodetectors 201 to 206, and supplies the photoreceiving signal to the amplifier circuit 7.
The amplifier circuit 7 amplifies the photoreceiving signal supplied from the photoreceiving selection circuit 6, converts the amplified signal from an analog signal to a digital signal and supplies the same to the microcomputer 8. The microcomputer 8 compares the level of the supplied photoreceiving signal with a prescribed reference level, and determines whether or not an object has been detected, on the basis of the comparison result. In other words, the microcomputer 8 makes a determination that presence of an object is not detected when the level of the photoreceiving signal is in excess of the reference level, while making a determination that presence of an object has been detected when the level of the photoreceiving signal is lower than the reference level. The microcomputer 8 supplies a signal indicating such a determination result to the output circuit 9. The output circuit 9 outputs an object detection signal capable of indicating presence/absence of existence of an object in response to the signal supplied from the microcomputer 8. This object detection signal is employed for operations of various types of units in the aforementioned object detection.
When a plurality of such multi-optical axis photoelectric switches where projectors and photoreceivers are paired are used, there is a possibility of mutual interference, resulting in an erroneous detection, if the multi-optical axis photoelectric switches are arranged in such a manner that the photoreceiver of a certain multi-optical axis photoelectric switch possibly receives light emitted from the projector of another multi-optical axis photoelectric switch. The mutual interference in this case stands for the following phenomenon: When the projectors simultaneously perform projecting operations in the respective ones of two multi-optical axis photoelectric switches, for example, the photoreceiver in one multi-optical axis photoelectric switch may receive light emitted by the projector in the other multi-optical axis photoelectric switch. In such a case, it is possible that an object actually present is not detected, since light emitted by the projector of one multi-optical axis photoelectric switch enters the photoreceiver of the other multi-optical axis photoelectric switch although a light intercepting state is caused by the object between the projector and the photoreceiver of the one multi-optical axis photoelectric switch. Such a phenomenon in that projected light beams mutually interfere between a plurality of multi-optical axis photoelectric switches is called mutual interference.
As a method of preventing such mutual interference, there is a method of adjusting projection timings of multi-optical axis photoelectric switches so that the projection timings do not coincide between a plurality of multi-optical axis photoelectric switches. Specifically, there is a control method of connecting a plurality of multi-optical axis photoelectric switches by a wire and transmitting a signal indicating the projection timing of a certain multi-optical axis photoelectric switch among the plurality of multi-optical axis photoelectric switches having the possibility of performing projection at the same time to another multi-optical axis photoelectric switch, so as to shift the projection timing so that the projection timing does not coincide with the other multi-optical axis photoelectric switch. In this case, the multi-optical axis photoelectric switch transmitting the signal indicating the projection timing is called a master multi-optical axis photoelectric switch, and the multi-optical axis photoelectric switch receiving the signal is called a slave multi-optical axis photoelectric switch. In other words, the master stands for a sensor controlling an operation start timing among the connected multi-optical axis photoelectric switches, and the slave stands for a sensor operating dependently on the master.
As a method of preventing mutual interference, there is also a method of adjusting setting of the frequency of a signal defining a projection timing by a setter such as a dip switch so that projection timings do not coincide among a plurality of multi-optical axis photoelectric switches.
An exemplary structure of a group of multi-optical axis photoelectric switches structured by connecting a plurality of multi-optical axis photoelectric switches is now described. FIG. 21 is a front elevational view of series-connected conventional multi-optical axis photoelectric switches. Referring to FIG. 21, a sensor 131 including a projector 131a and a photoreceiver 131b and a sensor 132 including a projector 132a and a photoreceiver 132b are connected in series. Here, an object detection signal is outputted from only one photoreceiver 131b. Such a series connection system is utilized not only for prevention of mutual interference but also for setting a non-detection area performing no detection of an object, and for creating an L-shaped structure setting a detection area in an L shape. Such a sensor connected in series is called an extension unit. This extension unit is connected to a multi-optical axis photoelectric switch that by itself functions as a sensor, and used for enlargement of the detection area, and the unit does not by itself attain the function of the sensor. When employing the series connection system, therefore, it is necessary to fabricate an extension unit independently of a multi-optical axis photoelectric switch functioning by itself as a sensor, and hence the fabrication cost for the sensor increases. When individual multi-optical axis photoelectric switches and extension units are used in combination and variations as to a detection area and detectability (the detectability depends on the distance between projective elements) of sensors are to be made, it is necessary to additionally increase the types of the sensors in consideration of the extension unit. Thus, there is such a problem that, when fabricating a multi-optical axis photoelectric switch and an extension unit, the fabrication cost for a sensor inclusive of the cost for inventory thereof further increases.
FIG. 22 is a front elevational view of multi-optical axis photoelectric switches having a structure for preventing mutual interference, employing dip switches. Referring to FIG. 22, each of a sensor 141 including a projector 141a and a photoreceiver 141b and a sensor 143 including a projector 143a and a photoreceiver 143b prevents mutual interference by changing frequency setting of projection timings by a dip switch 142 provided on each projector. FIG. 22 shows an example of preventing mutual interference between parallel-connected multi-optical axis photoelectric switches. This parallel connection is a connection system in which a plurality of multi-optical axis photoelectric switches individually outputting object detection signals are connected with a wire. The parallel connection is effective where multi-optical axis photoelectric switches are employed for a plurality of machines (press machines etc.) whose detection areas are different. On the contrary, series connection is effective where a plurality of multi-optical axis photoelectric switches are employed for a detection area of one machine.
Specific examples of use of multi-optical axis photoelectric switches are now described. FIG. 23A and FIG. 23B are perspective views illustrating specific examples of use of multi-optical axis photoelectric switches.
In FIG. 23A, there is shown an example of use of series-connected multi-optical axis photoelectric switches. A plurality of multi-optical axis photoelectric switches formed by projectors 10a and photoreceivers 10b are series-connected in a manner surrounding a working area on the front side of a working unit 50 performing an operation such as material processing. In this case, an object detection signal is outputted from one photoreceiver no matter which multi-optical axis photoelectric switch detects an object. In this case, an object to be detected intruding into one working area of one working unit is detected by a plurality of multi-optical axis photoelectric switches, and hence the series connection system is suitable. This is because one object detection signal is sufficient since the working unit 50 is at a risk no matter which detection area the object intrudes.
In FIG. 23B, there is shown an example of use of multi-optical axis photoelectric switches where working units are set in parallel. A multi-optical axis photoelectric switch is provided on the front side of each of two working units 51 and 52 individually performing an operation such as material processing. A multi-optical axis photoelectric switch formed by a projector 11a and a photoreceiver 11b is provided on the side of the working unit 51 in a manner surrounding a working area. A multi-optical axis photoelectric switch formed by a projector 13a and a photoreceiver 13b is provided on the side of the working unit 52 in a manner surrounding a working area.
When performing detection of an object by means of a group of multi-optical axis photoelectric switches structured by series-connecting such multi-optical axis photoelectric switches or the like, operations of a plurality of multi-optical axis photoelectric switches are generally controlled in a collective manner.
When operations are to be controlled in the general, collective manner in a group of operation units formed by a plurality of operating units such as in the case of the group of multi-optical axis photoelectric switches, the aforementioned connection of the operating units and setting of master/slave have been performed.
In a control unit performing general operation control of a plurality of operating units such as the aforementioned multi-optical axis photoelectric switches, it is necessary to adjust setting of the frequency of a signal defining a projection timing by a set switch such as a dip switch in order to prevent mutual interference for the operating units provided in a parallel direction. In order to prevent mutual interference among a number of multi-optical axis photoelectric switches, therefore, the same number of set switches are required, and a set operation for preventing mutual interference is extremely complicated. There has been such a problem that a complicated setting operation possibly leads to erroneous setting. Further, it has been possible to parallel-connect up to only two pairs of multi-optical axis photoelectric switches when the multi-optical axis photoelectric switches are to be connected in parallel by means of a wire. When performing connection employing an extension unit as described above, there has been such an additional problem that the extension unit can be employed only for series connection providing limited versatility. When employing the extension unit, further, there has been such a problem that the fabrication cost increases for the aforementioned reason.
The present invention has been proposed in order to solve the aforementioned problems. An object of the present invention is, when a control unit is provided on each of a plurality operating units for generally controlling a group of a plurality of operating units performing a certain operation to enable regular operation control, to provide a control unit which can by itself determine whether it is a master operating unit or a slave operating unit and can improve convenience for the user.
Still another object of the present invention is to provide a control unit which can improve the degree of freedom in changing a manner of connection of an operating unit group and the degree of freedom in expanding operating units.
A further object of the present invention is to provide a control unit which can communicate with an adjacent operating unit.
A further object of the present invention is to provide a control unit which can determine whether or not a manner of serial or parallel connection with an operating unit as an object of connection is an erroneous connection.
A further object of the present invention is to provide a control unit which can make determinations as to whether or not an operating unit provided with the control unit for general operation control of an operating unit group is connected with other operating units on a higher side and a lower side of control order.
A further object of the present invention is to provide a control unit which can, when performing general operation control of an operating unit group, make a determination as to whether operating units are connected in series or connected in parallel.
A further object of the present invention is to provide a control unit which can, when performing general operation control of an operating unit group, decide a master operating unit on the basis of connection states to a higher side and a lower side of the operating unit.
A further object of the present invention is, when performing general operation control of an operating unit group, to make it possible to transmit a control signal in accordance with the manner of series or parallel connection to another operating unit connected to an operating unit.
A further object of the present invention is to provide a control unit which can, when performing general operation control of an operating unit group, determine whether each of the operating units of the operating unit group is a master operating unit or a slave operating unit.
The present invention is directed to a control unit provided, in order to generally control a group of a plurality of operating units performing a certain operation formed connectable in series or in parallel as a whole to enable regular operation control, on each of said plurality of operating units, said control unit including: a communication part for communicating with the adjacent operating unit; a start position determination part for determining whether or not the operating unit is located on a predetermined start position as the most significant position of control order in the series connection or the parallel connection serving as a start point of general control in the operating unit group on the basis of relative positional relation obtained as a result of performing a communicating operation by the communication part; and a master/slave decision part for deciding the operating unit provided with the control part to be a master operating unit when it is determined by the start position determination part that it is located on the start position and deciding the operating unit provided with the control part to be a slave operating unit operating dependently on the master operating unit when it is determined by the start position determination part that it is not located on the start position.
The certain operation in this case means an operation including a detecting operation of a sensor or the like, for example. General control in this case means that a part of the operating unit group collectively controls/drives the group as a whole, for example. To communicate with the adjacent operating unit in this case means to mutually exchange signals between connected adjacent operating units by a method such as transmission/reception of the signals, for example. The start position in this case means a position serving as a prescribed reference as the most significant position of control order in series connection or parallel connection, such as a start position of general operation control or the like. A rule in this case means a rule predetermined in relation to an operation of successively driving the operating unit group, for example. Basically, these interpretations are similarly applicable to the invention of the aspects described below.
Thus, communication is made by the communication part with the adjacent operating unit. Whether or not the unit is located on the predetermined start position serving as the start point of general control in the operating unit group is determined by the start position determination part on the basis of the relative positional relation obtained as the result of the communicating operation by the communication part. The operating unit provided with the control unit is decided to be the master operating unit when it is determined by the start position determination part that it is located on the start position, and the operating unit provided with the control unit is decided to be the slave operating unit operating dependently on the master operating unit when it is determined by the start position determination part that it is not located on the start position.
Therefore, each operating unit belonging to the operating unit group can determine whether it is a master operating unit or a slave operating unit itself Therefore, it is unnecessary for the user to perform setting as to master/slave for each operating unit. Thus, the convenience for the user can be improved. Further, each operating unit can determine whether it is a master operating unit or a slave operating unit on the basis of the relative positional relation to the adjacent operating unit, whereby each operating unit can be a master operating unit as well as a slave operating unit in accordance with the relative positional relation. Therefore, the degree of freedom in changing the manner of connection of the operating unit group and the degree of freedom expanding the operating units can be improved.
The communication part includes a first signal output part outputting a first signal toward the control unit of an operating unit connectable in series, a second signal output part outputting a second signal toward the control unit of an operating unit connectable in series or in parallel, a first signal input part receiving, when connected in series to the control unit of an operating unit as the object of connection, the first signal from the control unit, and a second signal input part receiving, when connected in series or in parallel with the control unit of an operating unit as the object of connection, the second signal from the control unit, the start position determination part determines whether or not the first signal input part has received the first signal and determines whether or not the second signal input part has received the second signal, and the master/slave decision part decides either a master operating unit or a slave operating unit on the basis of the determination result of the start position determination part.
Therefore, each operating unit can communicate with the connectable adjacent operating unit employing two types of signals. Thus, each operating unit itself can determine whether it is a master operating unit or a slave operating unit. Further, the operating unit can be employed for both series connection and parallel connection, and requires no separate part such as an extension unit dedicated to series connection. Thus, it is possible to provide an operating unit having high versatility, which can decrease inventory.
Further, the start position determination part further makes a determination of the type of the signal received by the first signal input part, and further makes a determination of the type of the signal received by the second signal input part. In addition, it includes an erroneous connection determination part making a determination as to whether or not erroneous connection is present in the manner of connection with the control unit of the operating unit as the object of connection, on the basis of the determination result of the signal received by the first signal input part and the determination result of the signal received by the second signal input part. Thus, determinations of the types of the received signals are further made, and a determination is made as to whether or not erroneous connection is present in the manner of connection with the control unit of the operating unit as the object of connection, on the basis of the determination results.
Therefore, each operating unit can determine, by itself, whether or not the state of serial or parallel connection with the operating unit as the object of connection is erroneous connection. Therefore, the user can readily find erroneous connection of such an operating unit group that includes a plurality of operating units, whereby the convenience for the user is improved and the safety can be improved.
According to another aspect, the present invention is directed to a control unit provided, in order to generally control a group of a plurality of operating units performing a certain operation formed connectable in series or in parallel as a whole to enable regular operation control in accordance with a prescribed control order, on each of said plurality of operating units, said control unit including:
a first transmitting/receiving part connectable to the operating unit on a higher side of said control order for performing transmission/reception of a signal to/from the operating unit on the higher side; a second transmitting/receiving part connectable to the operating unit on a lower side of said control order for performing transmission/reception of a signal to/from the operating unit on the lower side; and a determination part for determining whether or not the unit is connected with the operating unit on the higher side on the basis of a manner of reception of the signal by said first transmitting/receiving part and determining whether or not the unit is connected with the operating unit on the lower side on the basis of a manner of reception of the signal by said second transmitting/receiving part.
According to such a control unit, signals are transmitted/received to/from the operating units on the higher side and the lower side of the control order for determining whether or not it is connected with the operating unit on the higher side on the basis of the manner of reception, and determining whether or not it is connected with the operating unit on the lower side on the basis of the manner of reception of the signal by the second transmitting/receiving part. Therefore, it is possible to make determinations as to whether or not the operating unit provided with the control unit for performing general operation control of the operating unit group is connected with other operating units on the higher side and the lower side of the control order.
When the plurality of operating units are connectable in series and in parallel, the determination part further makes determinations as to whether the operating units connected to the respective ones of the higher side and the lower side of the control order are connected in series or connected in parallel, on the basis of the manner of reception of the signals by the first and second transmitting/receiving parts. In this case, the determination is made as to whether the operating units connected to the respective ones of the higher side and the lower side are connected in series or connected in parallel on the basis of the manner of reception of the signals received from the operating units on the higher side and the lower side of the control order, whereby the determination as to whether the operating units are connected in series or connected in parallel can be made when performing general operation control of the operating unit group.
According to still another aspect, the present invention is directed to a control unit provided, in order to generally control a group of a plurality of operating units performing a certain operation as a whole to enable regular operation control in accordance with a prescribed control order, on each of said plurality of operating units, said control unit including: a first transmitting/receiving part connectable to the operating unit on a higher side of said control order for performing transmission/reception of a signal to/from the operating unit on the higher side; a second transmitting/receiving part connectable to the operating unit on a lower side of said control order for performing transmission/reception of a signal to/from the operating unit on the lower side; and a determination part for determining whether or not the unit is connected with the operating unit on the higher side on the basis of a manner of reception of the signal by said first transmitting/receiving part and determining whether or not the unit is connected with the operating unit on the lower side on the basis of a manner of reception of the signal by said second transmitting/receiving part.
According to such a control unit, the signals are transmitted/received to/from the operating units on the higher side and the lower side of the control order for determining whether or not it is connected with the operating unit on the higher side on the basis of the manner of reception, and determining whether or not it is connected with the operating unit on the lower side on the basis of the manner of reception of the signal by the second transmitting/receiving part. Therefore, it is possible to make determinations as to whether or not the operating unit provided with the control unit for performing general operation control of the operating unit group is connected with other operating units on the higher side and the lower side of the control order.
Further included are: a start position determination part determining whether or not it is located on a predetermined start position serving as a start point of general control in the operating unit group on the basis of the determination result by the determination part as to whether or not it is connected with the operating unit on the higher side, and a master/slave decision part deciding the operating unit provided with the control unit to be a master operating unit when it is determined by the start position determination part that it is located on the start position and deciding the operating unit provided with the control unit to be a slave operating unit operating dependently on the master operating unit when it is determined by the start position determination part that it is not located on the start position. Thus, whether or not it is located on the predetermined start position serving as the start point of integrated control can be determined on the basis of the manner of reception of the signals received from the operating units on the higher side and the lower side of the control order, whereby the master operating unit can be decided on the basis of the connection states of the operating unit to the higher side and the lower side when performing general operation control of the operating unit group.
According to a further aspect, the present invention is directed to a control unit provided, in order to generally control a group of a plurality of operating units performing a certain operation as a whole to enable regular operation control, on each of said plurality of operating units, said control unit including: a control signal transmitting part for transmitting a control signal for performing said general operation control to another connected operating unit, wherein said control signal transmitting part transmits a first control signal for performing said general operation control when said another operating unit is connected in series and transmits a second control signal for performing said general operation control when said another operating unit is connected in parallel.
In this case, a signal for commanding an operation of the other operating unit connected in series, for example, is included in the first control signal for performing integrated operation control. Further, a signal for authorizing the other operating unit connected in parallel to operate is included in the second control signal for performing integrated operation control.
Thus, a control signal in accordance with the manner of series or parallel connection can be transmitted to the other operating unit connected to the operating unit when performing general operation control of the operating unit group, whereby the degree of freedom in changing the manner of connection of the operating unit group and the degree of freedom expanding the operating units can be improved.
According to a further aspect, the present invention is directed to a control unit provided, in order to generally control a group of a plurality of operating units performing a certain operation as a whole connected in series or in parallel to enable. regular operation control in accordance with a prescribed control order, on each of said plurality of operating units, said control unit including:
a signal transmitting/receiving part for performing transmission/reception of respective ones of a control signal transmitted to the operating unit on a lower side of the control order for commanding an operation of the operating unit on the lower side of the control order and an authorization signal transmitted to the operating unit on a higher side of the control order for authorizing an operation of the operating unit connected in parallel with respect to the remaining connected operating units for the integrated operation control; and
an operation control part for controlling such that said certain operation is executed when the signal transmitting/receiving part receives the control signal from the higher side of the control order, wherein said signal transmitting/receiving part further transmits the control signal to the operating unit on the lower side after the operation controlled by the operation control part in response to the control signal from the operating unit on the higher side terminates when the operating unit is connected in series on the lower side of the control order, and transmits said authorization signal to the operating unit on the higher side after the operation controlled by the operation control part terminates when the operating unit is not connected in series on the lower side of the control order.
When transmission/reception of the signals in such a mode is performed, it corresponds to the least significant operating unit among series-connected operating units, for example.
Thus, the control signal is successively transmitted from the higher side to the operating unit on the lower side, whereby the operating units forming the operating unit group successively operate. The authorization signal authorizing the operation of the operating unit connected in parallel is transmitted from the least significant operating unit among the operating units connected in series toward the operating unit on the higher side, whereby operating units connected in parallel can also be successively driven after operation termination of the series-connected operating units.
According to a further aspect, the present invention provides a control unit provided on each of a plurality of operating units for general control of a group of operating units performing a certain operation and connected in series or in parallel with each other to enable regular operation control in accordance with a prescribed control order, and the unit includes a signal transmitting/receiving part performing transmission/reception of respective ones of a control signal transmitted to an operating unit on a lower side of the control order for commanding an operation of the operating unit on the lower side of the control order and an authorization signal transmitted to an operating unit on a higher side of the control order for authorizing an operation of an operating unit connected in parallel with respect to connected other operating units for general operation control, and an operation control part performing such control that makes the certain operation executed when the signal transmitting/receiving part receives a control signal from the higher side of the control order, and the signal transmitting/receiving part further transmits the control signal to the operating unit on the lower side after the operation controlled by the operation control part in response to reception of the control signal from the operating unit on the higher side terminates, when the operating unit is connected in series to the higher side and the lower side of the control order, and further transmits the authorization signal to the operating unit on the higher side in response to reception of an authorization signal from the operating unit on the lower side of the control order. When transmission/reception of the signals in such a manner is performed, it corresponds to an intermediate operating unit between the most significant one and the least significant one among series-connected operating units, for example.
Thus, the control signal is successively transmitted from the higher side to the operating unit on the lower side, whereby the operating units forming the operating unit group successively operate. The authorization signal authorizing the operation of the operating unit connected in parallel is transmitted toward the operating unit on the higher side successively through operating units connected in series, whereby operating units connected in parallel can also be successively driven after the end of operation termination of the series-connected operating units.